Diffractive Optical Element for a Time-of-Flight Sensor and Method of Operation of Same

Abstract

A system and method of dynamically controlling a light source is described herein. Modulated light that includes an input signal riding on illumination light can be emitted in a monitoring area, and an object can be detected in the monitoring area and passively tracked. Based on passively tracking the object, tracking data associated with the object can be received. Based on the tracking data, the illumination light can be steered towards the object in the monitoring area to increase the amount of illumination light striking the object and steered away from one or more sections of the monitoring area that are unoccupied by the object. Reflections of the modulated light can be received from the object and based on the received reflections, a depth distance of the object can be provided.

What is claimed is: 
     
         1 . A time-of-flight sensor for dynamically controlling modulated light, comprising:
 a light source configured to emit modulated light in a monitoring area, wherein the modulated light is comprised of an input signal riding on illumination light;   a diffractive optical element optically coupled to the light source, wherein the diffractive optical element is configured to receive the modulated light and to modulate the illumination light of the modulated light; and   a processor that is communicatively coupled to the diffractive optical element, wherein the processor is configured to:
 receive tracking data from one or more sensors of a passive tracking system, wherein the tracking data is associated with an original object in the monitoring area being passively tracked by the passive tracking system; 
 based on the tracking data, signal the diffractive optical element to adjust the modulation of the illumination light to steer the illumination light towards the original object in the monitoring area to increase the amount of illumination light striking the original object and to steer the illumination light away from one or more sections of the monitoring area unoccupied by the original object. 
   
     
     
         2 . The time-of-flight sensor of  claim 1 , wherein the diffractive optical element is a spatial light modulator that is configured to modulate the phase or amplitude of the illumination light. 
     
     
         3 . The time-of-flight sensor of  claim 1 , wherein the diffractive optical element is configured to modulate the illumination light without affecting the input signal. 
     
     
         4 . The time-of-flight sensor of  claim 1 , wherein the tracking data includes new positional data associated with the original object that corresponds to movement of the original object to a new location in the monitoring area. 
     
     
         5 . The time-of-flight sensor of  claim 4 , wherein the processor is further configured to, based on the new positional data, signal the diffractive optical element to adjust the modulation of the illumination light to steer the illumination light towards the original object at the new location and to steer the illumination light away from one or more updated sections of the monitoring area unoccupied by the original object. 
     
     
         6 . The time-of-flight sensor of  claim 1 , wherein the tracking data is associated with both the original object and a new object in the monitoring area being passively tracked by the passive tracking system and wherein the processor is further configured to, based on the tracking data, signal the diffractive optical element to adjust the modulation of the illumination light to steer the illumination light towards both the original object and the new object in the monitoring area and to steer the illumination light away from one or more sections of the monitoring area unoccupied by both the original object and the new object. 
     
     
         7 . The time-of-flight sensor of  claim 1 , further comprising a detector configured to receive reflections of the modulated light from the original object and the processor is further configured to determine a depth distance of the original object based on the received reflections of modulated light. 
     
     
         8 . The time-of-flight sensor of  claim 1 , wherein the processor is communicatively coupled to the light source and the processor is further configured to signal the light source to adjust the wavelength of the illumination light. 
     
     
         9 . The time-of-flight sensor of  claim 1 , wherein the time-of-flight sensor is a sensor that is part of the passive tracking system and the one or more sensors of the passive tracking system further comprise a visible-light sensor, a thermal sensor, or a sonar device. 
     
     
         10 . The time-of-flight sensor of  claim 1 , wherein the original object is a human and the processor is further configured to:
 receive tracking data from the sensors that indicates the lack of presence of the human; and   in response to the lack of presence of the human, deactivate the light source.   
     
     
         11 . A method of dynamically controlling a light source, comprising:
 emitting in a monitoring area modulated light that includes an input signal riding on illumination light;   detecting an original object in the monitoring area and passively tracking the object;   based on passively tracking the original object, receiving tracking data associated with the original object;   based on the tracking data, steering the illumination light towards the original object in the monitoring area to increase the amount of illumination light striking the original object and away from one or more sections of the monitoring area that are unoccupied by the original object;   receiving reflections of the modulated light from the original object; and   based on the received reflections, providing a depth distance of the original object in the monitoring area.   
     
     
         12 . The method of  claim 11 , wherein passively tracking the object comprises passively tracking the object with one or more sensors of a passive tracking system, wherein the sensors comprise a visible-light sensor, a thermal sensor, a time-of-flight sensor, or a sonar device and receiving the tracking data associated with the original object comprises receiving the tracking data from one or more of the visible-light sensor, the thermal sensor, the time-of-flight sensor, or the sonar device. 
     
     
         13 . The method of  claim 11 , wherein steering the illumination light towards the original object in the monitoring area and away from one or more sections of the monitoring area that are unoccupied by the original object is facilitated by selectively modulating the phase or amplitude of the illumination light. 
     
     
         14 . The method of  claim 11 , wherein steering the illumination light towards the original object in the monitoring area and away from one or more sections of the monitoring area that are unoccupied by the original object is facilitated by selectively adjusting the wavelength of the illumination light. 
     
     
         15 . The method of  claim 11 , further comprising:
 receiving updated tracking data associated with the original object indicating the original object has moved to a new location in the monitoring area;   based on the updated tracking data, steering the illumination light towards the new location of the original object in the monitoring area and away from one or more updated sections of the monitoring area that are unoccupied by the original object.   
     
     
         16 . The method of  claim 15 , further comprising:
 receiving reflections of the modulated light from the original object in the new location of the monitoring area; and   based on the received reflections of the modulated light from the original object in the new location, providing an updated depth distance of the original object in the monitoring area.   
     
     
         17 . The method of  claim 11 , further comprising:
 receiving updated tracking data associated with the original object and a new object in the monitoring area at the same time as the original object;   based on the updated tracking data, steering the illumination light towards both the original object and the new object in the monitoring area and away from one or more sections of the monitoring area that are unoccupied by both the original object and the new object.   
     
     
         18 . A method of increasing an operating range of a time-of-flight sensor in a monitoring area while simultaneously reducing the effects of multipath propagation arising from the operation of the time-of-flight sensor, comprising:
 emitting from the time-of-flight sensor modulated light that includes an input signal riding on non-visible illumination light;   receiving tracking data associated with an object in the monitoring area;   based on the tracking data, modulating the phase of the illumination light to steer the illumination light towards the object in the monitoring area to increase the amount of illumination light directed at the object and away from one or more sections of the monitoring area that are unoccupied by the original object to minimize the amount of illumination light reaching the sections;   receiving reflections of the modulated light from the object; and   based on the received reflections, providing a depth distance of the object in the monitoring area.   
     
     
         19 . The method of  claim 18 , wherein receiving tracking data associated with the object comprises receiving tracking data associated with the object from one or more sensors of a passive tracking system configured to passively track the object in the monitoring area. 
     
     
         20 . The method of  claim 18 , further comprising:
 receiving updated tracking data associated with the object that indicates the object is in a new location of the monitoring area;   based on the updated tracking data, modulating the phase of the illumination light to steer the illumination light towards the new location of the object and away from one or more updated sections of the monitoring area that are unoccupied by the object, wherein the updated sections include sections previously and newly unoccupied by the object.   
     
     
         21 . The method of  claim 18 , further comprising:
 determining that the object is within a predetermined distance of the time-of-flight sensor; and   based on the determination, correspondingly diffusing the steered illumination light to reduce the increased amount of illumination light directed at the object.